{"id":36661,"date":"2021-10-23T00:01:14","date_gmt":"2021-10-23T07:01:14","guid":{"rendered":"https:\/\/hakaimagazine.com\/?post_type=custom_news&p=36661"},"modified":"2021-10-22T16:09:31","modified_gmt":"2021-10-22T23:09:31","slug":"climate-change-is-kicking-up-the-difficulty-on-baby-shark-hide-and-seek","status":"publish","type":"custom_news","link":"https:\/\/hakaimagazine.com\/news\/climate-change-is-kicking-up-the-difficulty-on-baby-shark-hide-and-seek\/","title":{"rendered":"Climate Change Is Kicking up the Difficulty on Baby Shark Hide-and-Seek"},"content":{"rendered":"

What to do when you\u2019re an embryonic small-spotted catshark still growing in your translucent egg case and a ravenous predator is mere moments away from gobbling you whole? Wrap yourself up in your tail, hold your breath, and then freeze\u2014hoping that your mortal enemy fails to spot you drifting in the tangled seaweed. Catsharks, like several other species of sharks and rays, have evolved the intriguing ability to freeze their respiration for minutes at a time and hide mechanosensory and olfactory cues from passing snails, lobsters, and whelks. But according to a recent study<\/a>, the ability is being put at risk by a greater enemy still: climate change.<\/p>\n

Dan Ripley, a graduate student at the University of Manchester in England and the study\u2019s lead author, says that while scientists know about the sharks\u2019 defensive freezing ability, what wasn\u2019t known was how it might be affected by rising water temperatures. Most sharks are cold blooded, meaning their metabolic rate is modulated by their environment. Ripley and his colleagues hypothesized that, in warmer water, catshark embryos would burn through their oxygen more quickly\u2014and be able to freeze for far less time.<\/p>\n

To test their idea, the group placed several embryonic catsharks inside a custom respirometry chamber to measure their rate of oxygen uptake as a gauge of their metabolic rate. After triggering the catsharks\u2019 freezing response by gently tapping each egg case, they compared how long each could hold its breath.<\/p>\n

Your browser does not support the video element.<\/p><\/video>\n

A gentle prod of its egg case causes a small-spotted catshark to freeze. Video courtesy of Sara de Giorgio\/University of Manchester<\/span><\/p>\n

The most striking result, says Ripley, is that catshark embryos that were in water at a more familiar 15\u00a0\u00b0C could maintain the freezing behavior seven times longer on average than those in 20\u00a0\u00b0C water. This means that rising water temperatures could make embryonic small-spotted catsharks more vulnerable to predation. But the result, says Ripley, may also extend to the myriad other sharks and rays that lay eggs\u2014many of which are nearing the point of extinction<\/a>.<\/p>\n

For Gareth Fraser, an expert in shark development at the University of Florida, the study provides a valuable insight into how mechanical processes that are typically hidden can affect the vulnerability of embryonic sharks. He hopes that future research will examine other variables, such as ocean acidification. \u201cAs you shift the environment in which these organisms live \u2026 other predators may evolve or adapt to feed on them,\u201d says Fraser.<\/p>\n

Fraser says water temperatures around 20\u00a0\u00b0C are at the higher end of what catshark embryos are likely to experience in the wild. \u201cIt is a fairly extreme temperature change,\u201d concedes Ripley. Nevertheless, Ripley says that as marine heatwaves increase in frequency<\/a>, it is a temperature \u201cthat a shark in the wild could conceivably come across within the not-so-distant future.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

What to do when you\u2019re an embryonic small-spotted catshark still growing in your translucent egg case and a ravenous predator is mere moments away from gobbling you whole? Wrap yourself up in your tail, hold your breath, and then freeze\u2014hoping <\/p>\n

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